Genome-wide deletion distribution of HBV in northern China. Upper panel: The nucleotide location of deletions along the viral genome (X axis) and their counts (Y axis) in deletion mutations resolved from 51 whole genome sequences. Numbers at X indicate nucleotide position with the EcoR1 site at the preS1 region as 0. Middle panel: The ORFs for all genes, 4 domains of the P gene, and the BCP region. Bottom Panel: Alignment of detected deletions with viral epitopes in C (left) and the BCP/X region (right). 3 core deletions identified in clone sequencing were also included in addition to 4 deletions observed in whole genome sequences. The two arrows (bottom right) stand for nt 1762 and 1764 position, respectively. Known B- and T-cell epitopes in the C protein  are numbered from N- to C-terminus.